/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License.  You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package javax.servlet;

import java.util.EventListener;

	/**
	 * ServletContext 属性事件监听.
	 *
	 * ServletContextAttributeListener主要负责监听ServletContext的属性变化，包括属性的增加、删除和修改，
	 * 实现ServletContextAttributeListener可以接收属性变化事件
	 *
	 * Implementations of this interface receive notifications of
	** changes to the attribute list on the servlet context of a web application. 
	* To receive notification events, the implementation class
	* must be configured in the deployment descriptor for the web application.
	* @see ServletContextAttributeEvent
	 * @since	v 2.3
	*/

public interface ServletContextAttributeListener extends EventListener {
	/**
	 * ServletContext新增属性事件.在属性新增后调用.
	 * Notification that a new attribute was added to the servlet context. Called after the attribute is added.
	 */
public void attributeAdded(ServletContextAttributeEvent scab);


	/**
	 * ServletContext移除属性事件.在属性移除后调用.
	 *
	 * Notification that an existing attribute has been removed from the servlet context. Called after the attribute is removed.
	 */
public void attributeRemoved(ServletContextAttributeEvent scab);


	/**
	 * ServletContext替换属性（即修改）事件.在属性替换后调用.
	 *
	 * Notification that an attribute on the servlet context has been replaced. Called after the attribute is replaced.
	 */
public void attributeReplaced(ServletContextAttributeEvent scab);
}

